This invention relates generally to optical surveillance and more particularly to covert surveillance assemblies with means for optically scanning an object area and to covert surveillance assemblies wherein the detectability of surveillance is minimized or reduced.
In conventional scanning systems, the image sensor, for example, a charge-coupled device ("CCD"), is fixed to the camera casing. Scanning of an area is achieved by pivoting the entire camera about one or more separate rotational axes.
Prior camera systems having mechanisms for scanning a visual field or object area are disclosed in U.S. Pat. Nos. 4,024,573, 4,05I,523, 4,499,490, 4,661,855 and 4,707,743.
U.S. Pat. No. 4,024,573 to Carnes discloses a TV camera provided with a double-dove prism rotatably mounted in front of the camera lens, whereby the camera is capable of scanning a field extending nearly 360.degree. around the camera.
U.S. Pat. No. 4,051,523 to Laikin et al. describes and illustrates a submersible television camera capable of scanning an angle of 180.degree. from one side to the other by virtue of a lens mounted for rotating through 90.degree. on each side of the lens' normal axis.
U.S. Pat. No. 4,499,490 to Morgan is directed to a scanning video camera assembly which includes an apparatus for moving a mirror about a horizontal axis and a vertical axis to achieve a multidirectional scan.
U.S. Pat. No. 4,661,855 to Gulck shows and describes a television camera wherein a light sensing element particularly in the form of a recording or camera tube is mounted in an insert in turn swivelably mounted to a camera housing by means of a universal joint. At a light receiving end the recording or camera tube has a photocathode disposed behind a focusing lens attached to the camera housing. An electrically controllable positioning motor swivels the camera insert in each or two mutually perpendicular planes to vary the viewing direction of the camera. The television camera disclosed by Gulck is designed for use in viewing the insides of sewer pipes.
U.S. Pat. No. 4,707,743 to Tokumitsu et al. relates to a method and apparatus for converting a image into filtered electrical signals. In a specific form of the apparatus illustrated in FIG. 8, the image is transmitted to a planar CCD via a lens and two swivelable mirrors. The CCD is exposed more than once to the image. Charges induced in each exposure are added upon shifting the charge positions in the CCD and are subsequently extracted as electrical signals.